Enzyme-assisted immune detection of plant virus proteins electroblotted onto nitrocellulose paper

Alterations of housekeeping proteins in human aged and diseased hearts

Pathological remodeling includes alterations of ion channel function and calcium homeostasis and ultimately cardiac maladaptive function during the process of disease development. Biochemical assays are important approaches for assessing protein abundance and post-translational modification of ion channels. Several housekeeping proteins are commonly used as internal controls to minimize loading variabilities in immunoblotting protein assays. Yet, emerging evidence suggests that some housekeeping proteins may be abnormally altered under certain pathological conditions. However, alterations of housekeeping proteins in aged and diseased human hearts remain unclear. In the current study, immunoblotting was applied to measure three commonly used housekeeping proteins (β-actin, calsequestrin, and GAPDH) in well-procured human right atria (RA) and left ventricles (LV) from diabetic, heart failure, and aged human organ donors. Linear regression analysis suggested that the amounts of linearly loaded total proteins and quantified intensity of total proteins from either Ponceau S (PS) blot-stained or Coomassie Blue (CB) gel-stained images were highly correlated. Thus, all immunoblotting data were normalized with quantitative CB or PS data to calibrate potential loading variabilities. In the human heart, β-actin was reduced in diabetic RA and LV, while GAPDH was altered in aged and diabetic RA but not LV. Calsequestrin, an important Ca2+ regulatory protein, was significantly changed in aged, diabetic, and ischemic failing hearts. Intriguingly, expression levels of all three proteins were unchanged in non-ischemic failing human LV. Overall, alterations of human housekeeping proteins are heart chamber specific and disease context dependent. The choice of immunoblotting loading controls should be carefully evaluated. Usage of CB or PS total protein analysis could be a viable alternative approach for some complicated pathological specimens.

Comparative Investigations of the Sandfish’s β-Keratin (Reptilia: Scincidae: Scincus scincus). Part 1: Surface and Molecular Examinations

The Sandfish (Scincidae: Scincus Scincus) Is a Lizard Capable of Moving through Desert Sand in a Swimming-Like Fashion. the Epidermis of this Lizard Shows a High Resistance against Abrasion Together with a Low Friction to Sand as an Adaption to a Subterranean Life below the Desert’s Surface, Outperforming even Steel. the Low Friction Is Mainly Caused by Chemical Composition of the Scales, which Consist of Glycosylated β-Keratins. in this Study, the Friction, the Micro-Structure, the Glycosylation of the β-Keratin Proteins and β-Keratin Coding DNA of the Sandfish in Comparison to other Reptilian Species Was Investigated, Mainly with the Closely Related Berber Skink (Scincidae: Eumeces Schneideri) and another Sand Swimming Species, the Not Closer Related Shovel-Snouted Lizard (Lacertidae: Meroles Anchietae). Glycosylated β-Keratins of the Sandfish, Visualized with Different Lectins Resulted in O-Linked Glycans through PNA Employed as Carbohydrate Marker. Furthermore, the Glycosylation of β-Keratins in Various Squamatean Species Was Investigated and All Species Tested Were Found Positive; however, it Seems Like both Sand Swimming Species Examined Have a much Stronger Glycosylation of their β-Keratins. in Order to Prove this Finding through a Genetic Foundation, DNA of a β-Keratin Coding Gene of the Sandfish Was Sequenced and Compared with a Homologue Gene of Eumeces Schneideri. by Comparison of the Protein Sequence, a Higher Abundance of O-Glycosylation Sites Was Found in the Sandfish (enabled through the Amino Acids Serine and Threonine), Giving Molecular Support for a Higher Glycosylation of the β-Keratins in this Species.

Cloning and expression of antiviral/ribosome-inactivating protein from Bougainvillea xbuttiana

A full-length cDNA encoding ribosome-inactivating/antiviral protein (RIP/AVP)from the leaves of Bougainvillea x buttiana was isolated. The cDNA consisted of 1364 nucleotides with an open reading frame (ORF)of 960 nucleotides encoding a 35.49 kDa protein of 319 amino acids. The deduced amino acid sequence has a putative active domain conserved in RIPs/AVPs and shows a varying phylogenetic relationship to the RIPs from other plant species. The deduced protein has been designated BBAP1 (Bougainvillea x buttiana antiviral protein1). The ORF was cloned into an expression vector and expressed in E.coli as a fusion protein of approximately 78 kDa. The cleaved and purified recombinant BBAP1 exhibited ribosome-inhibiting rRNA N-glycosidase activity,and imparted a high level of resistance against the tobacco mosaic virus (TMV).

Antigenic characteristics as taxonomic criterion of differentiation of Alternaria spp., pathogenic for carrot and parsley

Identification of Alternaria genus species is a very complicated process which demands broadly designed investigations and studying of great number of properties which together can be considered as satisfying taxonomic criteria. The main objective of these investigations was examining the possibilities of applying the antigenic characteristics of Alternaria spp. phytopathogenic fungi as a taxonomic criterion, as well as introducing the serological methods for their identification. Conducting the examination of Alternaria spp., pathogenic for Apiaceae plants in Serbia, several isolates were obtained and identified as Alternaria radicina, A. petroselini, A. dauci and A. alternata, based on the conventional mycological methods and host range, as well as on molecular detection and partial characterization. The investigation included 12 isolates from plant leaves, seeds and soil which were pathogenic mainly to carrot and parsley and were identified as A. radicina, A. petroselini, A. dauci and A. alternate. Investigated isolates were compared with each other, as well as with standard isolates for the mentioned species (a total of 5 isolates, originating from USA and EU). During the investigation of serological characteristics of Alternaria spp. firstly a polyclonal antiserum was prepared against one isolate from Serbia identified as A. dauci. This antiserum was specific to Alternaria genus while there was no reaction with antigens from other phytopathogenic fungi genera (Fusarium, Rhizoctonia and Agaricus). Antiserum titer, determined by slide agglutination test, was 1/32. Antigenic characteristics of Alternaria genus fungi were examined by Electro-Blot-Immunoassay serological method (EBIA, Western blot), i.e. their protein profiles were compared. Investigated Alternaria spp. isolates showed different protein band profiles in gel and on nitrocellulose paper, and the observed differences were in complete correlation with the results of the previous identification. All investigated isolates, both domestic and the standards, were similar to each other, and they could be correctly identified to the species level using EBIA. Besides grouping to the species level, antigenic characteristics indicated similarities and differences among the isolates within the same and different species, showing their complex relationships which properly reflect their diversity in nature. In all the previous investigations of Alternaria genus fungi up to now, there have been no data about their serological characteristics as possible taxonomic criteria. Introduction of this group of characteristics represents an important contribution both to the taxonomy and implementation of fast and accurate methods of phytopathogenic fungi identification.

β-Actin is not a reliable loading control in Western blot analysis

Beta-actin is often used as a loading control in Western blot analysis. We analyzed the ability of beta-actin-specific antibodies to recognize differences in protein loading. We found that, at higher total protein loads as required for the detection of low-abundance proteins, beta-actin-specific antibodies failed to distinguish differences in actin protein levels. Diluting the antibody working solution or changing the incubation time had little effect on this phenomenon. This shows that beta-Actin is not a reliable loading control in Western blot analysis. In general, it appeared that, at longer incubation times, antibodies seem to be less able to pick up differences in the level of its target protein.

Molecular cloning and nucleotide sequencing of the 3'-terminal region of a South African isolate of ryegrass mosaic virus RNA and in vitro expression of the coat protein gene

The 2094 nucleotides at the 3'-terminus of a South African isolate of ryegrass mosaic virus (RGMV) was cloned and sequenced. Two putative polyprotein cleavage sites were found: Q/L and E/A, both of which are novel in the Potyviridae. The RGMV-SA cDNA was cloned into an expression vector, pUEX, and a fusion protein of 185 kDa was obtained which reacted strongly to anti-RGMV-SA antiserum. Alignment of the predicted amino acid sequence of RGMV-SA with those of other Potyviridae members showed limited identity, indicating that RGMV-SA is a definite and distinct virus.

Cloning, sequencing, and expression in Escherichia coli of the coat protein gene of a new potyvirus infection South African Passiflora

Complementary DNA representing 1418 nucleotides (nt) of the 3'-poly(A)-proximal tract of the genomic RNA of a potyvirus causing woodiness disease in South African passion fruit, was cloned and sequenced. The sequence contained a single long open reading frame (ORF) of 1188 nt with no initiation codon, and a 3'-non-coding region (3'-NCR) of 230 nt followed by a poly-adenylate tract. Comparison of the ORF with other potyviral coat protein (CP) sequences led to the prediction that a 279 residue CP of MW 31722 is encoded by 836 nt at the 3'-terminus of the ORF. This virus is not merely a South African strain of passion fruit woodiness virus (PWV): the deduced CP sequence is only distantly related to CPs of other sequenced strains of PWV, although it is part of a distinct subgroup of potyviruses related to PWV. The virus was therefore designated as South African passiflora virus (SAPV). The DNA containing the putative CP was cloned into the pUEX2 bacterial expression vector and expressed in Escherichia coli as a beta-gal-CP fusion protein. The fusion protein reacted with polyclonal antisera raised against the native virus, and antisera raised against partially purified fusion protein reacted with viral CP in Western blots.

Fungal transmission of a potyvirus: uredospores of Puccinia sorghi transmit maize dwarf mosaic virus

Maize dwarf mosaic virus (MDMV) and maize rust, Puccinia sorghi Schw., occur as natural infections on cultivated maize in South Africa. P. sorghi often occurs as a secondary late infection on maize plants which have already been infected with MDMV earlier in the season, either seed or aphid transmitted. When MDMV isolates from maize plants naturally infected by both virus and fungus were propagated by sap inoculation in plant growth rooms, residual uredospores in the sap gave rise to the development of uredia under conditions of high humidity. When uredospores developing on MDMV-B-infected plants were germinated on virus free maize seedlings, these plants became infected with MDMV-B. Similarly, when uredospores, originating from maize plants infected with MDMV-A, were scattered onto virus free maize seedlings, these plants became infected with MDMV-A. The presence of virus on uredospores in infected plant tissue was visualized by indirect immunofluorescence. Identification of virus infection was by DAS-ELISA and immunoelectro-blotting utilizing strain-specific antisera. Virus transmission occurred between closely situated plants which had no actual contact (unaided transmission). MDMV-B transmission by uredospores, to new maize seedlings, has been maintained for three successive years (1988-1991) in a plant growth room. The MDMV-B isolate remained sap and non-persistently aphid transmissible.

Cloning and expression of a Clostridium thermocellum DNA fragment that encodes a protein related to cellulosome component SL

Antibodies raised against the SL subunit of the Clostridium thermocellum cellulosome were used to screen a library of C. thermocellum chromosomal DNA fragments constructed in the vector lambda gt11. A DNA fragment that encoded a polypeptide that crossreacted with the anti-SL antibodies was isolated and its restriction map elucidated. No similarity with other previously cloned DNA fragments has been found. The anti-SL crossreacting polypeptide was isolated from recombinant Escherichia coli and found to have a mol mass of 37,000 Da and to possess low levels of CMCase and Avicelase activity. Using CMC as the substrate, a temperature optimum of 55 degrees C and a pH optimum of 6.6 were observed. These properties were compared to those of C. thermocellum SL isolated by electroelution from an SDS gel, which was also found to possess low levels of CMCase and Avicelase activities. In addition, the SL proteins produced in C. thermocellum and E. coli were able to interact positively against Avicel with an endoglucanase (Ss) purified from the C. thermocellum crude cellulase preparation, and with a recombinant protein that crossreacted with anti-Ss antibodies.

Serological techniques for detection of citrus tristeza virus

Citrus tristeza virus (CTV) is the most economically important virus disease of citrus. In the last ten years, remarkable progress has been achieved in the development and improvement of new serological methods for CTV detection so that serology has become a dependable tool for many research, extension and regulatory purposes worldwide. CTV-specific polyclonal antisera and monoclonal antibodies have been developed in different research laboratories and used extensively in a wide range of different studies. This review describes the diverse serological methods developed for CTV detection and analyzes the advantages, disadvantages, relative sensitivity, applications, and present status of each method.

Purification and characterization of endoglucanase Ss from Clostridium thermocellum

The extracellular cellulolytic enzymes of the thermophilic anaerobe Clostridium thermocellum occur as a protein complex or aggregate known as the cellulosome. By using a combination of ion-exchange, adsorption and hydrophobic-interaction chromatography, it was possible to isolate from extracellular broth a specific endoglucanase of interest without the use of denaturants. The endoglucanase was identified as the cellulosomal subunit Ss by the use of specific antibodies. The enzyme has an Mr of 83,000, an isoelectric point of 3.55, optimum pH of 6.6 and optimum temperature of 70 degrees C. It hydrolyses CM-cellulose and, at a higher rate, the cellodextrins, cellotetraose and cellopentaose, but does not hydrolyse a crystalline cellulose such as Avicel. Cellobiose and cellotriose are also immune to attack. It differs from endoglucanases previously isolated by others and a 76,000-Mr endoglucanase recently isolated in this laboratory.

Cloning, nucleotide sequence, and enzymatic characterization of an alpha-amylase from the ruminal bacterium Butyrivibrio fibrisolvens H17c

A Butyrivibrio fibrisolvens amylase gene was cloned and expressed by using its own promoter on the recombinant plasmid pBAMY100 in Escherichia coli. The amylase gene consisted of an open reading frame of 2,931 bp encoding a protein of 976 amino acids with a calculated Mr of 106,964. In E. coli(pBAMY100), more than 86% of the active amylase was located in the periplasm, and TnphoA fusion experiments showed that the enzyme had a functional signal peptide. The B. fibrisolvens amylase is a calcium metalloenzyme, and three conserved putative calcium-binding residues were identified. The amylase showed high sequence homology with other alpha-amylases in the three highly conserved regions which constitute the active centers. These and other conserved regions were located in the N-terminal half, and no similarity with any other amylase was detected in the remainder of the protein. Deletion of approximately 40% of the C-terminal portion of the amylase did not result in loss of amylolytic activity. The B. fibrisolvens amylase was identified as an endo-alpha-amylase by hydrolysis of the Phadebas amylase substrate, hydrolysis of gamma-cyclodextrin to maltotriose, maltose, and glucose and the characteristic shape of the blue value and reducing sugar curves. Maltotriose was the major initial hydrolysis product from starch, although extended incubation resulted in its hydrolysis to maltose and glucose.

The use of serological differentiation indices for the phylogenetic analysis of plant virus relationships

The potential use of serological differentiation indices (SDIs) in the phylogenetic analysis of plant virus coat protein relationships is presented. Relationship dendrograms were constructed from SDI data for viruses in the tymovirus and Subgroup I geminivirus taxonomic groups, using distance or phenetic methods embodied in the computer programmes FITCH and NJTREE. Relationship dendrograms for geminiviruses agreed well with those constructed by others from sequence or other data; the dendrogram for tymoviruses was not in agreement with one calculated from amino acid composition data, or from other properties, but appears consistent with recently-shown sequence similarities between tymoviruses. Implications of these results for the classification and taxonomy of plant viruses are discussed.

Reducing agents interfere with the detection of lettuce necrotic yellows virus in infected plants by immunoblotting with monoclonal antibodies

A procedure is described for the detection of lettuce necrotic yellows virus (LNYV) nucleocapsid protein (N) or envelope glycoprotein (G) by immuno-blotting with their respective monoclonal antibodies. The antigens can be detected in 1-10 mg of fresh tissue from systemically infected Nicotiana glutinosa leaves showing prominent symptoms. The composition of the extraction buffer played a crucial role in the recovery of antigenically active proteins. Procedures involving tissue extraction in the presence of the reducing agents 2-mercaptoethanol (2-ME) or dithiothreitol (DTT) failed to detect either the N or G antigen. For optimum detection of the N or G antigens, leaf tissue was ground with 10 mM phosphate buffer, pH 7.6 (PB), containing 3% (w/v) sodium dodecyl sulphate (SDS) and 1 mM of the protease inhibitor N-p-tosyl-L-lysine chloromethyl ketone (TLCK). The extract was then mixed with an equal volume of dissociation buffer containing 2-ME before electrophoresis and immunoblotting.

Possible members of the potyvirus group transmitted by mites or whiteflies share epitopes with aphid-transmitted definitive members of the group

There are at least ten viruses identified in the literature that resemble definitive potyviruses in having flexuous filamentous particles and inducing the formation of "pinwheel" cytoplasmic inclusions in infected cells but that are transmitted by eriophyid mites, whiteflies or soil fungi and not by aphids, the vectors of the definitive potyviruses. The taxonomic status of these viruses is uncertain at present. Using a broadly cross-reactive antiserum raised against the dissociated coat protein core (residues 68-285) of a definitive potyvirus (Johnsongrass mosaic virus), we have shown that wheat streak mosaic virus which is transmitted by mite and sweet potato mild mottle virus which is transmitted by whitefly have coat proteins that share epitopes with definitive potyviruses. This finding further supports their classification as definitive members of the potyvirus group. The cross-reactive antiserum used here had been shown previously to react with coat proteins of fifteen different definitive potyviruses. The antiserum did not react with coat proteins of potexviruses and tobamoviruses.

Purification and characterisation of glutamine synthetase from Nocardia corallina

Glutamine synthetase (GS) (EC 6.3.1.2) has been purified 67-fold from Nocardia corallina. The apparent Mr of the GS subunit was approximately 56,000. Assuming the enzyme is a typical dodecamer this indicates a particle mass for the undissociated enzyme of 672,000. The GS is regulated by adenylylation and deadenylylation, and subject to feedback inhibition by alanine and glycine. The pH profiles assayed by the gamma-glutamyl transferase method were similar for NH+4-treated and untreated cell extracts and an isoactivity point was not obtained from these curves. GS activity was repressed by (NH4)2SO4 and glutamate. Cells grown in the presence of glutamine, alanine, proline and histidine had enhanced levels of GS activity. The GS of N. corallina cross-reacted with antisera prepared against GS from a Gram-negative Thiobacillus ferrooxidans strain but not with antisera raised against GS from a Gram-positive Clostridium acetobutylicum strain.

Cloning and expression in Escherichia coli of a recA-like gene from Bacteroides fragilis

The recombinant plasmid pHG100, containing a 5.2-kb DNA fragment from Bacteroides fragilis, complemented defects in homologous recombination, DNA repair and prophage induction to various levels in an Escherichia coli recA mutant strain. There was no DNA homology between the cloned B. fragilis recA-like gene and E. coli chromosomal DNA. pHG100 produced two proteins with Mr of approx. 39,000 and 37,000 which cross-reacted with antibodies raised against E. coli RecA protein. The production of these proteins was not increased after UV induction. The cloned B. fragilis recA-like gene product did not enhance the production of native but defective E. coli RecA protein after UV irradiation.

Temperature and oxygen regulated expression of a glutamine synthetase gene from Vibrio alginolyticus cloned in Escherichia coli

Glutamine synthetase (GS) synthesis in Vibrio alginolyticus was regulated by temperature, oxygen and nitrogen levels. A GS gene, glnA from V. alginolyticus was cloned on a 5.67 kb insert in the recombinant plasmid pRM210, which enabled Escherichia coli glnA, ntrB, ntrC deletion mutants to utilize (NH4)2SO4 as a sole source of nitrogen. The V. alginolyticus glnA gene was expressed from a regulatory region contained within the cloned fragment. V. alginolyticus glnA expression from pRM210 was subject to regulation by temperature, oxygen and nitrogen levels. GS specific activity in an E. coli wild-type strain was not affected by temperature or oxygen. pRM211 was a deletion derivative of pRM210 and GS production by pRM211 was not regulated by temperature, oxygen or nitrogen levels in E. coli.

Protein synthesis in Rift Valley fever virus-infected cells

Rift Valley fever virus-induced protein synthesis was examined by polyacrylamide gel electrophoresis and fluorography. Five virus-induced polypeptides were detected, the nucleocapsid protein N, the nucleus-associated nonstructural protein NS1, the glycoproteins G1 and G2, and a protein of molecular weight 80K. The N, G1, G2, and 80K proteins were present in virion preparations. Sequential studies showed that NS1 accumulated in the nucleus as soon as it was formed and readily associated with nuclei partitioned from noninfected cells. The G1 and G2 proteins labelled with [3H]glucosamine and [3H]mannose. NS1 was shown to be the only virus-induced protein which was phosphorylated.

Detection of partially proteolysed cauliflower mosaic virus coat protein in infected leaf tissue by Western blotting

Cauliflower mosaic virus (CaMV) capsid polypeptides were detected by immunoelectroblotting ('Western blotting') 10-16 days after infection of Chinese cabbage leaves. The predominant polypeptides detected had molecular weights of 42,000 and 37,000 suggesting that in vivo proteolysis of the 55,000-58,000 molecular weight coat protein had taken place. The use of laboratory-made nitrocellulose membranes for Western blotting is reported. Phosphate-SDS buffer was more suitable than Tris-glycine buffer for the electrophoretic transfer of CaMV polypeptides. Specific antibodies prepared by absorption to intact CaMV were used as a probe for the viral coat proteins.